AMBIENTUM BIOETHICA BIOLOGIA CHEMIA DIGITALIA DRAMATICA EDUCATIO ARTIS GYMNAST. ENGINEERING EPHEMERIDES EUROPAEA GEOGRAPHIA GEOLOGIA HISTORIA HISTORIA ARTIUM INFORMATICA IURISPRUDENTIA MATHEMATICA MUSICA NEGOTIA OECONOMICA PHILOLOGIA PHILOSOPHIA PHYSICA POLITICA PSYCHOLOGIA-PAEDAGOGIA SOCIOLOGIA THEOLOGIA CATHOLICA THEOLOGIA CATHOLICA LATIN THEOLOGIA GR.-CATH. VARAD THEOLOGIA ORTHODOXA THEOLOGIA REF. TRANSYLVAN
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STUDIA CHEMIA - Ediţia nr.1 din 2005 | |||||||
Articol: |
DISCONTINUUM BETWEEN FERROUS-SUPEROXO AND FERRIC-PEROXO IN HEME [FEO2]9 COMPLEXES?. Autori: RADU SILAGHI-DUMITRESCU, IOAN SILAGHI-DUMITRESCU. |
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Rezumat: Low-spin [FeO2]9 complexes (where the superscript denotes the sum of iron d electrons and dioxygen * electrons), generally described as ferric-peroxo or ferrous-superoxo, have been implicated in the catalytic cycles of heme and non-heme proteins. Experimental observation of these complexes, mainly by ENDOR spectroscopy, has led to two distinct descriptions of heme [FeO2]9, depending on whether or not hydrogen bonding to the oxygen ligand is available. Hydrogen-bonded [FeO2]9 were described as ferric-peroxo, while non hydrogen-bonded [FeO2]9 were described as ferrous-superoxo. Reported here is a DFT investigation of the effects of hydrogen bonding on the structure of heme [FeO2]9 complexes. Calculated bond lengths, spin densities and hyperfine couplings all argue against a ferrous-superoxo/ferric-peroxo discontinuum. Possible implications of this finding are discussed. | |||||||